The present invention relates to a magnetic recording medium such as a magnetic disk and more particularly to a magnetic recording medium having a metallic thin film with excellent corrosion-resistivity and slide-resistivity.
In order to realize high density recording on a magnetic recording medium such as a magnetic disk, the characteristic of a recording film has been improved and the film has been made thin. Also, a spacing between the recording medium and a recording/reproducing head has been reduced.
The recording medium having a ferromagnetic metallic thin film, formed through sputtering, as a recording film permits the recording film to be satisfactorily improved in its characteristic and made thin. However, such a magnetic recording medium requires a protection layer or lubrication layer or a composite of both protection and lubrication layers in order to maintain the characteristic of the recording film and to improve the corrosion-resistivity thereof and the slide-resistivity thereof in view of the sliding movement of a magnetic head, as disclosed in JP-A-57-30124. Namely, the magnetic recording medium according to this prior art does not consider improving the corrosion-resistivity and slide-resistivity of the recording film itself which is made of a ferromagnetic metallic thin film. Therefore, if the protection film or the lubrication film which is provided on the recording film to improve the corrosion-resistivity or slide-resistivity thereof, contains some pinhole or local disappearance, the recording medium may begin to degrade in the region corresponding to that site, thus deteriorating the reliability of the magnetic recording medium.
In order to obviate the above problem, it has been proposed to impregnate the recording film itself with lubricant to improve the corrosion-resistivity and slide-resistivity of the recording film itself. Also, in order to further improve the corrosion-resistivity and slide-resistivity of the recording film itself, it has been proposed to store the lubricant in many minute pores or grooves formed on the recording film surface using a grinding paper or the like, thereby increasing the amount of the lubricant impregnated in the recording film, as disclosed in JP-A-55-117741 and JP-A-55-113632. Further, it has been also proposed to impregnate the protection film formed on the recording film or an additional layer underlying the recording film with the lubricant through many minute pores or grooves formed on the surface thereof, as disclosed in JP-A-61-94235, JP-A-60-5423 and JP-A-59-84328.
However, the above technique of providing many minute pores or grooves on the recording film surface for increasing the amount of lubricant impregnated in the recording film has a problem of deteriorating the recording characteristic since these pores or grooves do not pertain to the recording of information.
This technique, which requires an extra step, also makes the entire fabricating process of a magnetic recording medium complicated and expensive.
Further, the above technique of providing minute pores or grooves in the protection film or underlying layer, which requires an additional processing step, makes the fabricating process more complicate.